Optical demultiplexer, optical multi-/demultiplexer, and optical device

摘要

The present invention provides an optical demultiplexer and an optical multi-/demultiplexer at low cost without reducing performance capabilities. An optical demultiplexer (100a) includes: a multi-mode waveguide (102a) having such an optical path length as to cause a difference between first and second wavelengths with respect to a phase difference between zero- and first-order modes to become an integral multiple of pi ; an input waveguide (105a) optically connected to the input side of the multi-mode waveguide (102a) such that the optical axis thereof is offset from the center line of the multi-mode waveguide (102a); and two output waveguides (103a and 104a) optically coupled to the multi-mode waveguide (102a) at different positions of the output side of the multi-mode waveguide (102a). The two output waveguides (103a and 104a) are located in such a manner as to maximize the extinction ratio.